Adjustable wave guide joint



March 1, 1949. w, ARON ET AL 2,463,347

' ADJUSTABLE WAVEGUIDE JOINT Filed May a, 1946- FIG. I

FIG.2

F IG. 3

' INVENTORS 24 2 WALTER ARON FRANCIS E. EHLERS 5 BY ArrbR/ve'r Patented Mar. 1, 1949 ADJUSTABLE WAVE GUIDE JOINT Walter Aron, Berkeley, Calif., and Francis Edward Ehlers, Providence, R. I., assignors, by mesne assignments, to the United States of America as represented by the Secretary of War Application May 8, 1946, Serial No. 668,245

3 Claims. 1

This invention relates to waveguides, and particularly to an improved form of movable or Wobble to allow angular movement between two guide sections.

Couplings which permitted angular movement between waveguide sections have previously been open to the objection of having substantial radiation loss. Commonly, choke couplings have been used cut back to permit the desired movement. This cutback arrangement introduced relatively large spaces between the moving parts, and. the radiation loss became increasingly large as the spacing increased. The present invention uses a universal joint which has only a very small gap, and keeps the gap a constant size at any angle through which the joint may be turned.

The invention is illustrated in the drawing, in which:

Fig. 1 is a sectional view of a wobble joint incorporating the invention, taken as indicated by line I--I in Fig. 2;

Fig. 2 is a bottom view of the embodiment shown sectionally in Fig. 1; and

Fig. 3 is a fragmentary view similar to that of Fig. 1, but showing a modification of the invention.

The wobble joint shown in Fig. 1 includes two joined rectangular outer housing blocks I and 2 in which a seat 4 is centrally formed in the shape of a spherical segment. Within the spherically curved seat 4 is movably disposed a snugly fitting spherical segment 5 having a closed end 6 and an open end I. A waveguide section 9, which is illustrated as being of conventional rectangular crosssection, is fixed to the closed end 6 and opens into the space within the spherical segment 5. Outer housin blocks I and 2 may be assembled about segment 5 after the spherically curved portions which combine to form seat 4 have been machined, and secured by means described hereafter.

Segment 5 is internally bored to form a radial choke ID, or cylindrical cavity, the axis of revolution of which is coincident with the center of symmetry of the waveguide section 9. The radius of the cavity is so selected that the walls II, defining the boundary of the choke Ill, are effectively one-half wavelength from the waveguide wall 9. By effectively one-half wavelength is meant that the radius selected is the one which causes the standing wave ratio in the waveguide sections to be a minimum.

It is desirable to construct the joint with a step in the flat surface a quarter wavelength from the outside of the cavity. This is the region at which the choke currents are a minimum, and hence is most desirable for the break in the conducting surface necessary in broad banding the joint.

This step includes a disc member I2 inserted into a bore I4 formed in segment 5. Bore I4 is coaxial with but of larger diameter than choke I 9, and the juncture therebetween forms a shoulder I5, against which disc I 6 is seated. Disc I B has a bore I I formed therethrough of such diameter that the spacing between the bore and choke wall I I will be one-quarter wavelength. The bore then constitutes the beginnning of the step or break in the cavity. Within bore I "I is movably disposed an inner spherical segment I9 which is about three times the thickness of disc member I2, and is spaced symmetrically about the same center of revolution as the disc I2 and spherical segment 5.

Through the center of inner spherical member I9 is fixed a waveguide member 20. When the inner spherical segment I9 and the spherical segment 5 are properly alined, the center lines of waveguide sections 9 and 20 will coincide.

A bracket 2| is used to hold waveguide 29 fixed relative to the outer housing block 2. The bracket may be secured to the housing block 2 by bolts 22 which also serve to hold blocks I and 2 together. When the waveguide section 9 is tilted, either with or without rotation, the outer spherical segment 5 is free to turn in any desired direction within the seat 4. Disc l2 will maintain close contact with the inner spherical segment I9 throughout such movement, since the centers of the spherical surfaces of members 5 and I9 are the same.

In the event that it is desired to permit motion of the waveguide member 9 relative to guide member 20 in one plane only, a pin 20, shown in Fig. 3, may be adjustably inserted in the housing 2, and a keyway 2I cut into the surface of segment 5 to receive the end 24 of the pin.

It will be apparent that with the construction shown, openings at the joints through which undesired radiation can occur have been substantially eliminated. Regardless of the angle between the' waveguides 9 and 20, there is the same effective separation between them, and the presence of the choke I'Il minimizes radiation loss. Other connecting means, such as gimbal rings, might be substituted for those elements now joining segment 5 and guide I9.

What is claimed is:

1. Means for connecting a first waveguide section to a second waveguide section while permitting angular movement between the axes thereof. comprising a hollow spherical segment having a closed end through which said first guide section is fixed, the wall of said hollow segment being spaced effectively one-half wavelength about said first guide section, a spherically curved seat rotatably surrounding said hollow segment, means for rigidly connecting said seat to said second waveguide section, an inner spherical segment terminally disposed about said second waveguide section within said hollow spherical segment, a substantially thinner disc having an annular width of one-quarter wavelength movably disposed symmetrically about said inner spheriical segment and fixed within said hollow spherical segment, and means for restricting said an! nular movement to movement within one plane.

2. A coupling for waveguide sections arranged to permit relative angular movement therebetween, comprising a hollow spherical segment having a closed end through which a waveguide may be secured, a spherically curved seat in which said segment may be held rotatably, a second waveguide section, means, for joining said second section to said seat, an inner spherical segment fixed about said second waveguide section, and a disc substantially thinner than said segment disposed movably about said inner spherical segment and fixed within said hollow segment; said hollow segment portion having its wal p ce f ti el n a1f wave ngth about said waveguide section one-quarter wavelength from said inner spherical segment.

3. A microwave wobble joint, comprising a spherical segment having a waveguide fixed thereto, a seat curved congruently about said segment and arranged for movement relative thereto, a cylindrical cavity formed within said segment extending effectivelyhalf a wavelength outwardly from said waveguide, a disc closing off said cylindrical cavity, said disc having a bore therethrough one-quarter wavelength inwardly from the Walls of said choke, an inner spherical segment substantially thicker than said disc disposed Within said bore for relative movement between said segment and said disc, and a waveguide disposed through said inner spherical segment.

WALTER. ARON. FRANCIS EDWARD EHLERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,407,3l8 Mieher Sept. 10, 1946 2,420,007 Olden May 6, 1947 

